Telephone-exchange system



Jan. 7, 1980. F. s. IRVINE TELEPHONE EXCHANGE SYSTEM 1 E Y, MM R t m t m w w m m h k m N r m W a a v mt m 6 8 n A mt w t t m 0 7 Y l l 1 l 5 w l 1 v p w W JW h m Q A J M Q Q m v \QsQ h$6\ 1 m2 NQNPD L w ENEEE W @WWWL QQ Pl I f HI v 4 hl warm MIIIII QQW. QM ms iv: .H m g 7%? 5* Mia n Jan. 7, 1930. F. s. IRVINE 1,742,916

TELEPHONE EXCHANGE SYS TEM- Filed June 20. 1928 8 Sheets-Sheet 2 m w Q Q 3 Q N 2Q |H l I-v FRANK 5 /RV/NE 5r 9.6 Jm'y r A r TOHNE y Jan. 7, 1930. F. s. IRVINE I TELEPHONE EXCHANGE SYSTEM Filed June 20. 1928 8 Sheets-Sheet 3 NM QM h ink INVENTOR V FRANK 5. ['FV/NE 5r A T TOHNE Y Jan. 7,1930. F. s. IRVINE 1,742,916

I TELEPHONE EXCHANGE SYSTEM Filed June 20, :1928 8 Sheets-Sheet 4 /N VE N TOR FRANK 5 /R V/NE 5r ATTORNEY Filed June 2 O, 1928 8 Shets-Sheet m P Qkk /NVEN7'0H FRANK 5. /R VINE 5 Y A 7'7'0RNE Y Nah 8 Shets-Sheet Filed June 20. 1928 /NVEN RANK 5. /RV/NE A VTTOFINEY Jan. 7, 1930. F. s. IRVINE 1,742,916

TELEPHONE EXCHANGE SYSTEM Filed June 20, 1928 8 Sheets-Sheet 7 745 746 FINAL 70/ 4 6 6 IN VE N 70/? FRANK .51 /RV/NE By A TTOHNE Y Jan. 7, 1930.

Filed June 20, 1928 8 Sheets-Sheet 8 WW L W W W L W I A? u Mr L.

7 3 WL ML FIE m mi JLUL M JLUL GROUP 2 w r F W W? w /NVEN 7'OR BYFRAN/f .5. /RV/NE @aamw A rmx /ygy GROUP 4 GROUP 3 Patented Jan. 7' 1930 UNITED STATES PATENT? OFFICE FRANK S. IRVINE, 0F GREENLAWN, NEW YORK, ASSIGNOB TO BELL TELEPHONE LAB- ORATOBIES, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK TELEPHONE-EXCHAN GE SYSTEM Application filed June 20,

This invention relates to a telephone exchange system employing automatic selector switches and more particularly to a system employing a repeating sender associable with the incoming ends of interoffice trunks, to which the numerical portion of a wanted line number is transferred from the subscribers sender and which in turn controls the setting of the selector switches at the terminating office. The invention has for its object the more accurate control of selector switches over long interoflice trunks and the simplification of apparatus for repeating control impulses from one sender to another.

In large machine switching telephone exchanges it often occurs that certain offices of such exchanges are located at the outskirts of such areas and that therefore long interofiice trunks are necessary to interconnect certain offices which may be quite widely separated. Under these conditions the revertivc control of panel type selectors over such long trunks is not always reliable since the fixed speed at which the selectors at the terminating office operate on local connections may be faster than can be accurately controlled from a sender in an originating office, especially where a long length of interoffice cable intervenes. Heretofore, it has been the prac tice to establish such connections through a tandem switching ofice, the digits registered on the sender in an originating office being first transferred to a sender in the tandem office, which latter sender then controls the setting of the selectors in the terminating oflice. Unless the exchange area is very large and comprises a large number of offices, such tandem offices are not warranted from an economical standpoint and direct trunking between offices of the area is desirable.

A tandem trunking system of the type above described is illustrated in the patent to IV. L. Dodge, No. 1,531,080, issued March 24, 1925. In this system the office and line designations registered on the registers of the sender in the originating oflice are transferred to the registers of the tandem sender by the so-called relay call indicator pulse method. That is. for each digit registered in the first sender a special code of impulses 1928. Serial No. 286,813.

of negative and positive polarity is trans mitted to the tandem sender which is arranged to receive and register such codes on relay registers in much the same manner as impulses are transmitted to and registered in the well known call indicators. For local calls of a full mechanical nature the originating sender functions in the well known manner to control selector switches by impulses sent to the sender revertively by the selectors. Since such tandem senders must perform substantially all of the functions of the senders in the originating office, they must of necessity be as complicated in structure and function as such originating senders.

In accordance with the present invention calls from originating ofiices may be trunked directly to terminating offices without extension through a tandem office. This is accomplished through the provision of a group of small repeating or so-called spill senders in each office accessible in common to all interoflice incoming trunks. Each of these senders comprises a means for sending trains of revertive impulses back to the originating sender in the same manner that impulses are revertively sent from a selector switch commutator to satisfy the originating sender in accordance with the line designation digits registered on the registers thereof. The registers of the repeating sender are set in accordance with the impulses of each train so sent and therefore assume settings equivalent to the settings of the registers of the sender in the originating office. Counting relays are also provided which count the impulses so transmitted and assist in the setting of the registers and also in the usual manner count the impulses later transmitted from the selectors of the terminating office to control the setting of such selectors in accordance with the setting of the sender registers.

Each sender is also provided with means comprising an additional or 11th pair of counting relays which function in case the sender is not properly controlled from the originating sender during the revertive transmission of impulses back to the originating sender and transmits an excessive number of impulses, to set up an overflow condition in the sender whereby the -s ender is released from the interofiice trunk-with which it is at the time associated and another equivalent sender is taken for use. Provision is also made for enabling the sender and any selector switches which have been set thereby to be restored in the event. that the calling subscriber abandons a call at any time before the connection to the desired line has become established.

Provision is also made for enabling idle, preselected senders to be very quickly associated with any calling trunk of a large group of interoflice trunks. For this n ose the roup of interoflice trunks is divided into our sub-groups and the senders are similarly divided into our sub-groups. Each sender has individual thereto a pair of trunk finding switches each having access to 100 trunks whereby each sender has access to all of the trunks of a trunk group. Normally all of the senders of one sub-group have access to a sub-group of trunks through one of the trunk finders individual thereto, one sender of each sub-group being normally pre-allotted for use. For starting a pre-allotted sendertrunk-finder to hunt for a calling trunk in the sub-group which it normally serves, each subgroup of trunks has individual thereto a common start circuit. In the event that all senders in the sub-group normally assigned for connection with the trunks of a sub-group are busy at the time another call is initiated in such sub-group of trunks, the start circuit for such sub-group of trunks is extended for starting a pre-allotted sender in the next subgroup of senders. This start circuit may be similarly extended to all of the sub-groups of senders so that any idle sender in any of the sub-groups may be employed. The banks ofthe trunk finders are divided into two sections each and the trunks are all so multipled be-' tween the sections of the banks of all trunk finders associated with the four sub-groups of senders that they appear as first choice trunks in the banks of the finders associated with two successive sub-groups of senders and as second choice trunks in the banks of the finders associated with the next two successive sub-groups of senders.

The apparatus of the repeating sender is thus very simple and since it controls the transfer of registrations to its registers revertively in the same manner as selectors control their own settings, it is not necessary to employ special call indicator code apparatus in originating senders for this purpose but the same apparatus employed in the originating senders for setting selector switches may be emplo ed. Further, since there is no fixed speed 0 impulsing established such as is present in pulsing revertively from selector switches, the speed of impulsing from the repzating sender to the originating sender may ma e such as is more suitable for pulsing over longer interofiice cables than could be used for controlling selectors directly from the originating sender. This speed of imulsing may, however, be greater than would he attainable by the BS6 of the aforementioned relay call indicator method.

Considering the present invention in a general manner, calls to a terminating ofiice of an exchange area are extended in the well known manner by means of selector switches under the control of a register sender in an originating oflice in which the calling line terminates. When a call is incoming to an incoming selector in which aninteroflice trunk terminates a start circuit is closed to start a pair of trunk finders individual to an allotted repeating or spill sender of a group serving the group and incoming brush, and group, and final 9 brush, tens and units registers of the spill sender are set into correspondence with the similar registers of the originating sender. A fundamental switch controlling circuit is then established between the spill sender and incoming and final selectors of the terminating ofiice and such selectors are controlled from the spill sender in much the same manner as they would be controlled from the originating sender in accordance with the prior art. As soon as the originating sender as completed the transference of its registrations to the spill sender, the district selector is advanced into the talking position and such sender is dismissed. When the spill sender has completed its control of the incoming and final selectors it is alst dismissed.

The inventionhas been disclosed byway of illustration in the accompanying drawings in which Fig. 1 shows diagrammatically a calling line terminating in an automatic dial switching oflice having a line finder, district selector, ofiice selector and common sender; Fig. 2 shows an incoming selector of a terminating oifice of the exchange; Fig. 3 shows a final selector of such terminating ofiice and one subscribers line terminating therein Fig. 4 shows the start circuits of four sub-groups of incoming interoflice trunks; Figs. 5, 6 and 7, taken together, show one s ill sender of the terminating oflice, Fig. 5 s owing the A and B trunk finders and control circuits individual to one sender, Fig. 6 showing the 8 shows diagrammatically the multiplyin'gof the four sub-groups of trunks before the banks of the and B trunk finders of the four sub-groups of senders; and Fig. 9 shows the manner in which the figures of the drawing should be assembled to completely disclose the invention.

The apparatus of the originating oflice disclosed in Fig. 1 may be of the type fully disclosed in the patent to F. A. Stearn No. 1,505,171, granted August 19,1924. i

The trunk finders 510 and 520 of the spill sender, shown in Fig. 5, may be of the well known panel type with the exception that each finder is provided with but a single set of brushes and no tripping mechanism is pro-v vided. Two sequence switches are provided for controlling the spill sender. One of these sequence switches has a driving magnet 500 shown in Fig. 5. All the cams shown at the left of the dot and dash line of Fig. 5 and all of the cams shown in Fig. 6 with the exception of cams 605, 631, 63.3 and 638 are operated by magnet 500. The other sequence switch whose magnet is shown at 550 of Fig. 5 controls all of the cams shown at the right of the dot and dash line of Fig. 5 and cams 605, 631, 633 and 638 of Fig. 6.

Ewr'ensz'on of connection to spill s ender It is believed that the invention may be best understood from a detailed consideration of the manner in which a call may be established from the line of subscriber 100 in Fig. 1 to the line of subscriber 325 in Fig.

For this purpose it will be assumed that the number of subscriber 325 is CORtlandt 3983. When the calling subscriber removes his receiver from the switchhook his line hecomes extended by means of the line finder 101 to the district selector 102 and through link mechanism not shown to an idle sender diagrammatically illustrated by the rectangle 103. The line finder 101, district selector 102, sender 103 and link mechanism may be of the type disclosed in the patent to W. H. Matthies No. 1,567,072 granted December 29, 1925. A sender of the type disclosed at 103 is shown in detail in the patent to O. H. Kopp No. 1,589,402, granted June 22, 19,26.

Upon the extension of the calling line to the sender a pulsing circuit is established extending from battery, winding of pulsing relay 104, the left contact of cam 105, the ring brush of line finder 101 and the line terminal with which it is in engagement over the subscribers line loop, returning over the tip brush of line finder 101, the left contact of cam 106 to ground through the left winding of coil 107. Relay 104. energizes in this circuit, closing an obvious circuit for relay 108 which in turn establishes a tone circuit from the source 109 through the right winding of relay 107 the left contact of relay 108 to ground. A tone is thereby induced into the shown.

pulsin circuit and is heard by; the calling subscri er apprising him that e may commence to dial the office and numerical designations of the wanted line. In'the manner fully set forth in the aforementioned patent to Kopp, in response to the manipulamon or dial 110, the. oflice code and numerical reg isters of the sender are set to record the number of the wanted line. As soon as the ofiice code has been registered and the proper translation has been made in the sender, the sender proceeds in the well known manner to control the setting of the district selector 102 to extend the calling line to the terminals of an idle olfice selector 150. The control of this selector is exercised through the operation of the sender stepping relay 112 in conjunction with the usual train of counting relays, the last pair of which '113 and 114 are disclosed, and with the translator of the sender, not As soon as the district selector has found an idle oifice selector such as 150 the district sequence switch advances to position 10 in which position a controlling or fundamental circuit is extended from the sender to the oflice selector which may be traced in part from the tip brush of the district selector 102, the right contacts of cam 115, the back contact of counting relay 113, the winding of stepping relay 112, the upper left and lower right contacts of earn 116 to the ring brush of the district selector. The office selector 150 which is of the. well known type is then set from the translator of the sender to complete theextension of the calling line to the oflice in which the wanted line 325 terminates.

Upon the seizure of conductors 201 and 202 of an idle trunk terminating in'the incoming selector 250, the previously traced fundamental circuit is extended from the tip brush of the selector 102, over the tip brush of selector 150, conductor 201, the lower right contact of cam 203, resistance 204, to battery through the right winding of relay 205 and from the ring brush of the district selector 102, over the ring brush of oflice selector 150, conductor 202, the lower left contact of cam 206, to ground through the left winding of relay 205. Relays 112 and 205 energize in this circuit,

relay 112 preparing the sender for controlling the transfer of the incoming brush registration from the sender 103 to the sender of Figs. 5, 6 and 7. lVith sequence switch 200 in position 1, relay 205 upon energizing establishes a circuit for control relay 207, extending from battery, right Windin of relay .207, upper left contact of cam 208, ront contact of relay 205, right back contact of relay 209, to ground at the lower contact of cam 210.

Relay 207 energizes in this circuit and closes a start circuit for associating an idle sender with the trunk circuit 201, 202. This circuit extends from ground at the left front contact of relay 207, the upper right and lower left contacts of cam 211, start conductor 212, the upper back contact of relay 400, the left back contact of relay 401 to battery through the left winding of relay 402, provided there is an idle sender in the sub-group of senders normally assigned for serving the trunks in which trunk 201, 202 is locatr Relay 402 upon energizing extends the start conductor 212 over the upper back contact of relay 400, the outer right front contact of relay 402 to conductor 403, the outer left back contact of relay 501, the upper contact of cam 502, to battery 'through the ri ht winding of relay 503 and resistance 504. elay 503 upon energizing closes a circuit for advancing sequence switch 550 out of position 1 into position 2 extending from battery, winding of sequence switch magnet 550, the upper left contact of cam 505 to ground atthe right front contact of relay 503. With sequence switch 550 in position 2 relay 503 is locked from battery through resistance 504 and the right winding of relay 503, the lower left contact of cam 502, segment 507 of the commutator of switch 520, brush508 normally in engagement therewith, the upper contact of cam 509 to ground at the right front contact of relay 503. A circuit is also established for the up-drive magnet of switch 520 as follows: Battery, winding of up-drive magnet 511, the lower left contact of cam 509 to ground at the right front contact of relay 503. In response to the energization of magnet 511, the brushes of switch 520 are advanced to the first set of terminals connected to the first trunk of the group to which this trunk finder has access. It will be assumed that this trunk is in a noncalling condition and that the control relay thereof corresponding to relay v207 is deenergized. \Vhen the brushes of switch 520v are centered on the first set of terminals, the look ing circuit of relay 503 is opened at the commutator strip 507 as the brush 508 is then resting on an insulating segment thereof, but IJ- lay 503 is maintained energized over a locking circuit extending from battery at the upper right contact of cam 600, conductor 601, the left winding and inner left front contact of relay 503, brdging type test brush 512 and the terminal upon whic it is resting, overa conductor similar to conductor 513 thence over the left contacts of a cam similar to cam 213 to ground at the back contact of the control relay of that trunk similar to relay 207. Had such trunk beenengaged in the establishment of a connection and its sequence switch been advanced beyond position 1, then the conductor 513 would be grounded at the lower left contact of a cam similar to cam 214 and relay 503 would remain locked. With relay 503 thus locked the circuit of the updrive magnet 511 is maintained to advance the brushes of switch 520 to the next set of terminals.

It will. be assumed that the next set of terminals is connected as shown to the trunk 201, 202 and that the test conductor 513 is therefore open both at the back contact of relay 207 and at the contact of cam 214. Relay 503 thereupon releases, opening the circuit of magnet 511, stopping the brushes of the switch 520 upon the terminals of this trunk and closing a circuit extending from ground at the outer right back contact of relay 503 over the inner right back contact of relay 501, the lower left contact of cam 505 to battery through the magnet of sequence switch 550 advancing such sequence switch into position 3. Relay 503 upon releasing also connects ground over its inner left contact to test brush 512 to maintain busy potential upon the terminal upon which it is resting thereby preventing the brushes of another trunk finder associated with another sender finder from connecting therewith.

Relay 503 at its outer right back contact also establishes a circuit from ground over the inner right back contact of relay 501, the upper contacts of cam 517, conductor 404 to battery throughthe winding of relay 401. Relay 401 upon operating opens the start circuits through the windings of relay 402 to prevent the starting of another preallotted trunk finder until after the started trunk finder has found the calling trunk. With sequence switch 550 in position 3 a circuit is closed to advance se uence switch 500 out of position 1 into position 2 extending from battery through the winding of magnet 500, upper left contact of cam 514 to ground over the upperleft and lower right contacts of cam 515. A circuit is also established from ground at the outer right back contact of relay back contact of relay 501, the lower contact of cam 516, the upper contacts of cam 516 of a sender similar to the one disclosed whose sequence switch corresponding to 550 is standing in position 18 awaiting allotment, thence to the lower right contact of a cam similar to 505 to battery through the magnet of such sequence switch advancing such sequence switch into position 1 in readiness for serving the next incoming call.

At its inner right back contact relay 503 establishes a circuit extending from ground at the outer right back contact of relay 501, inner right back contact of relay 503, upper left contact of cam 518, brush 519, and the terminal upon which it is resting, conductor 405, upper contact of cam 215, winding of relay 209 to battery. ,Relay 209 energizes opening at its right back contact the circuit of relay 207 which in turn deenergizes, opening the circuit through relay 402, and at its right front contact closes a circuit for advancing sequence switch 200 out of position. 1 into position 2. This circuit may be traced from battery through the winding of magnet 200, lower left contact of cam 216, right 503, the inner right 201 over conductor 217, brush 521, the'lower right and upper left contacts of cam 522 to battery through the winding of control relay 523 and from trunk conductor 202 over conductor 218, brush 524, the left contacts of cam 525, theright back contact of relay 526 to ground at the upper left contact of cam 527. Relays 523 and 112 energize over the fundamental circuit. Relay 523 upon energizing closes a circuit for relay 528 from battery through the winding of relay 528, the front contact of relay 523 to ground at thelower left contact of cam 527. Relay 528 locks over its inner left front contact to ground at the lower right contact of cam 527, closing a holding circuit for itself directly to ground over its right front contact and the front/contact of relay 523 to prevent its deenergization after sequence switch 500 leaves position 2, and closing a circuit over its left front contact, upper right front contact of cam 51 1 through the winding of sequence switch 500 for advancing sequence switch 500 into position 3. With sequence switch 500 in position 3 the shunt which normally exists around relay 529 is removed at the left contacts of cam 527 and relay 529 energizes over the fundamental circuit.

Setting the sender registers Two circuits are now effective in parallel with each other, the first extending from battery over the left contact of cam 000- through the winding of the No. 9-count1ng relay of the train of counting relays d1sclosed at the bottom of Fig. 6, over the back contact of the No. 9' counting ,relay, conductor 602, the bottom contact of cam 530, the front contact of relay- 529, the lower contacts of cam 531, conductor 604 to ground at the upper right contacts of cam 603. The second circuit extends from ground-on conductor 604 over both contacts of cam 530 to battery through the winding of relay 532. Relay 532 and the No. 9-counting relay energize, the No. 9 counting-relay looking through the winding of the No. 9' counting relay, the front contact-of the No. 9

a counting relay, the lower contacts of cam 605 to ground at the lower contacts of cam 606. The No. 9 counting relay, however, does not energize in this locking circuit since at this time both-of its terminals are connected to ground. Bela 532 upon energizing closes an obvious ho ding circuit for relay 523 in shunt of relay 529 and also in shunt of the sender stepping relay 112. Both of these relays thereupon deenergize, the steppingrelay 112 causing upon its energization and deenergization the operation of a pair of counting relays of the sender 103 in the well known manner. Upon the deenergization of relay 529 ground is removed from one t rminal of the N o. 9 counting relay and this relay energizes in the locking circuit of the No. 9 counting relay. Thus a pair of counting relays in both the sender 103 and in the spill sender shown in Figs. 5, 6 and 7 have been operated and locked.

Upon the deenergization of relay 529, the energizing circuit of relay 532 is opened and the shunt again removed from the windings of relays 529 and 112 and these relays again energize, the relay 112 operating another.

counting relay of the next pair in the train of sender 103 and relay 529 again closing the circuit for operating relay 532 and in parallel therewith the No. 8 counting relay, over a circuit extendinig from conductor 602 through the front contact of the No. 9' counting relay, the back contact of the No. 8'

counting relay through the winding of the No. 8 counting relay to battery over the circuit previously traced. Relay 532 and the No. 8 counting relay energize, the No. 8 counting relay looking through the winding of" i the No. 8 counting relay and relay 532 again shunting the stepping relay 112 and the relay 529. This cycle of operations continues until the originating sender 103 is satisfied as to its incoming brush selection registration whereupon the fundamental circuit is opened at the sender 103 and relay 523 deenergizes.

Relay 523 upon deenergizing opens the holding circuit of relay 528, which latter relay deenergizes closing a circuit from battery through the magnet winding of sequence switch 500, the lower right contact of cam 514 for advancing sequence switch 500 into position 4. It has been assumed that the number of-the wanted subscriber 325 is 3983. Thus, two pairs of countin relays, No. 9

and No. 9 and No. 8 and o. 8' have beenoperated and locked to cause a registration of the fact that it will be necessary to trip the second set of brushes in the incoming selector 250. The manner in which this registration is set up on the incoming brush register relays of Fig. 7 will now be described.

When sequence switch 500 passes into position 3 a circuit is extended from battery over the lower contact of cam 600, conductor 701, both windings of register relay 700, conductor 702, the left contacts of cam 607, the back contact of No. '7 counting relay, the lower contacts of care. 805 to ground at the lower contact i: care 606. Until the No. 9

counting relay ene gizes, a shunt around the right winding of relay 700 exists which may be traced from the junction of the two windings of relay 7 00 over the left back contact of relay 7 00, conductor 703, the upper left and lower right contacts of the cam 608 to the back contact of the No: 9 counting relay to ground at the lower contact of cam 606. As soon as the No. 9 counting relay energizes relay 700 energizes.

A circuit is also established for relay 705 extending from battery over the lower contact of cam 600, conductor 7 01, both windings of relay 705, conductor 706, the left contacts of cam 609, the back contact of the No. 6 counting relay, the lower contacts of cam 605 to ground at the lower contact of cam 606. Until the No. 8 counting relay energizes there is a shunt around the right winding of relay 705 which may be traced from the junction of the two windings of relay 705 over the inner left back contact of relay 705 and conductor 707, the left contacts of cam 610, the back contact of the No. 8 counting relay to ground at the lower contact of cam 606; This shuntis opened at the back" contact of the No. 8 counting relay when that relay, is energized and relay 705 thereupon energizes.

A circuit is also established for relay 710 extending from battery, conductor 701, through both windings of relay 710, conductor 708, lower contact of cam 611, back contact of the No. 4 counting relay to ground as traced at the lower contact of cam 606. This relay, however, does not energize since its right winding is shunted over its outer right back contact, conductor 709, the right contacts of cam 612, the back contact of the No. 5 counting relay to ground at the lower contact of cam 606 and, since the No. 5 counting relay has not been energized this relay 710 cannot operate. Thus, in response to the operation of the counting relays two incoming brush selection register relays 700 and 705 have been operated and when sequence switch 500 advances into position 4 locking circuits are established therefor. The-locking circuit of relay 700 may be traced from battery, conductor 701, through both windings and the inner right contact of relay 7 00, conductor 7 04 to ground at the upper left contact of cam 606' The locking circuit for relay 705 may be traced from battery on the con- .ductor 701 through both windings and the inner right contact of relay 705, conductor 704 to ground at the upper left contact of cam 606. 4

It will be recalled that upon the termination of the transference of the incoming brush registration from the sender 103 to the spill sender that sequence switch 500 advanced into position 4. The fundamental circuit is now reestablished from battery throu h the winding of relay 523 thence as 5 trace to the winding of relay 112 at the tact and the upper contact of cam 514 for advancing sequence switch 500 into position 5. Relay 528 remains looked over the contact of relay 523 and its own right contact after sequence switch 500 leaves position 1. The operated counting relays No. 9, No. 9, No. 8 and No. 8 are at this time released as their locking circuits were opened at the lower contacts of cam 606 when sequence switch 500 passed out of position 3 With sequence switch 500 in position 5, the shunt around the winding of relay 529 is removed and this relay energizes over the fundamental circuit closing the previously traced parallel circuits through the winding of relay 532 and the winding of the No. 9 counting relay.

In the manner previously described relays 523, 529 and 112 cooperate to successively operate and lock pairs of counting relays 1n the spill sender and in the sender 103 until suflicient counting relays in the sender 103 have been operated to satisfy the incoming group registration therein, when the fundamental circuit will be opened through the operation of relay 113, releasing relays 523, 529 and 112. The release of relay 523 in the manner previously described opens the holding circuit of relay 528 which releases and causes the advance of sequence switch 500 into position 6. Since it has been assumed that the subscribers line number is 3983, it will be necessary to select a group of final selectors terminating in the fourth group of the second brush group of the incoming selector and therefore, four pairs of counting relays, No. 9, No. 9, No. 8, No. 8, No. 7, No. 7 and No. 6, No. 6 will be operated during the transferenceof the incoming group registration in the manner previously described.

As the sequence switch 500 passes into po sition 5, the following circuits will be established for. operating relays of the incoming group register: The first circuit extends from battery at the lower contact of, cam 600 'winding of relay 711 is shunted over acircuit from the junction point between the windings thereof over the left contact of relay 711, conductor 713, the lower contacts of cam 608, back contact of the No. 9 counting relay to ground at the lower contact of cam 606. As soon as the No. 9 counting relay en- 130 ergizes this shunt is opened and relay. 711 operates. A second circuit is also closed from the battery, conductor v701, through both windings of relay 715, conductor 716, the lower contacts of cam 609, the back contact of the No. 6 counting relay to ground at the lower contact of earn 606. Until the No. 8 counting relay energizes, relay 715 is shunted in a circuit from the junction point between the windings of relay 715, the inner left back contact of relay 715, conductor 717, the upper right and lower left contacts of cam 610, the back contact of the No. 8 counting relay to ground at the lower contact of cam 606.

As soon as the No. 8 counting relay energizes this shunt is opened and relay 715 operates. When the No. 7 counting relay operates the operating circuit of rela 711 is opened at the back contact of'the l\o. 7 counting relay and relay 711 deenergizes. As soon as the No. 6 counting relay operates the circuit of the relay 715 is opened at the back contact of the No. 7 counting relay. Thus, when the sequence switch advances out of position 5 into position 6 at the 'end of the transference of the incoming group registration, no relays of the incoming gr up register remain operated.

As sequence switch 500 leaves position 5 the locking circuits for the operated counting relays are opened at the lower contact of cam 606, and as the sequence switch arrives in position 6 relay 523 is again operated over the fundamental circuit in series with relay 112 of the sender 103. In the manner previously described relay 528 operates and locks upon the operation of relay 523, advancing sequence switch 500 into position 7 and thereby including relay 529 inthe fundamental circuit. Counting relays of the spill sender and of the sender 103 are thereupon operated and locked in the manner previously described until the sender 103 is satisfied as to its final brush registration when relay 113 operates, opening the fundamental circuit at the sender 103. Thereupon relays 112, 523 and 529'are deenergized, relay 523 unlocking relay 528 which in turn deenergizes advancing sequence switch 500 into position 8. Since it has been assumed that the subscribers number is 3983 the terminals of the wanted line will appear in thefifth brush group of the final selector and therefore five pairs of counting relays from No. 9, No. 9' to No. 5, No. 5 inclusive will have been operated.

Prior to the advance of sequence switch 500 out of position 7 a circuit will he effective from battery. on conductor 701 through .both windings of final brush register relay 718, conductor 719, the upper right and lower left contacts of cam 607, the back contact of the N0. 7 counting relay, the lower contacts of cam 605 to ground at the lower contact of cam 606. Until the No. 9 counting relay operates a shunt exists around the right winding of relay 718, extending from the junction point between its windings over the left contact of relay 718, conductor 720, the right contacts of cam 608, the back contact of the N0. 9 counting relay to battery. As

soon as the No. 9 counting relay operates this shunt is opened and relay 718 operates. A circuit is also closed from battery on condu'ctor 701, through both windings of relay 721, conductor 722, the upper right and lower left contacts of cam 609, the back contact of the No. 6 counting relay, thence to ground at the lower contact of cam 606. Until the No. 8 counting relay operates a shunt exists around the right winding of relay 721 extending from the junction point between its windings over the inner left back contact of relay 7 21, conductor 723, the lower contacts of cam 610, the back contact of the No. 8 counting relay to ground at the lower contact of cam 606. As soon as the No. 8 counting relay operates this shunt is opened and register relay 721 operates. A circuit is also established from battery on conductor 701, through both windings of relay 7 24, conductor 725, the lower contact of cam 613, the back contact of the No. 3 counting relay to ground at the lower contact of earn 606, and a shunt around the right winding of relay 724 exists from the junction of its two windings over its right back contact, conductor 726, the lower contacts of cam 612, the back contact of the No. 5 counting relay to ground at the lower contact of cam 606. This shunt is removed when the No. 5 counting relay energizes and relay 7 24 thereupon operates.

As soon as the No. 7 counting relay energizes the operating circuit ofrelay 718 is opened at the back contact of this counting relay and relay 718 releases. The operation of the No. 6 counting relay also opens the operating circuit of relay 7 21 at the back contact of the No. 6 counting relay and relay 7 21 releases. Thus at the end of the transference of the final brush registration from the sender 103, relay 7 24 is the only final brush register relay operated. This relay locks over its right front contact, conductor 727 to ground at the lower right contact of cam- 603 as soon as sequence switch 500 advances into position 7%.

When sequence switch 500 leaves position 7% the locking circuits for the operated counting relays are opened at the lower contact of cam 606 and as the sequence switch arrives in position 8 relay 523 is again operated over the fundamental circuit in series with relay 112 of the sender 103. In the manner previously described relay 528 operates and looks upon the operation of relay 523, ad-

vancing sequence switch 500 into position 9 and thereby including relay 529 in the funda mental circuit. Counting relays of the spill sender and of the sender 103 are thereupon operated and locked in the manner previously described until the sender 103 is satisfied I 500 out of position 9 a circuit will be effective til the No. 8 counting relay operates a shunt from battery on conductor 7 01, through both windings of relay 728, conductor 729, the upper left contact of cam 611, the back contact of the No. 4 counting relay to ground at the lower contact of cam 606. Until the No. 9 counting relay operates a shunt exists around the right winding of relay 728 extending from the junction between its windings, the left back contact of relay 728, conductor 730, the upper right contact of 'cam 614, the lower right contact of cam 608, the back contact of the No. 9 counting relay to ground at the lower contact of cam 606. As soon as the No. 9 counting relay operates this shunt is opened and relay 728 energizes. A circuit is also closed from battery on conductor 701, through both windings of relay 7 31, conductor 732, the upper left contact of cam 613, the back contact of the No. 3 counting relay to ground at the lower contact of cam 606. Un-

exists around the right winding of relay 731, extending from the junction between its windings over its inner left back contact,

conductor 733, the lower left contact of cam 615, the lower left contact of cam 610, the back contact of the No. 8 counting relay to ground at the lower contact of cam 606. As soon as the No. 8 counting relay operates this shunt ing relay to ground at the lower contact of cam 606. Until the No. 7 counting relay operates a shunt exists around the right winding of relay 7 34, extending from the unction between the windings thereof, over the inner left back contact of relay 734, conductor 736, the upper left contact of cam 617, the lower left contact of cam 607, the back contact of the No. 7 counting relay to ground at the back contact of cam 606. As soon as the No. 7 counting relay operates this shunt is opened and relay 734 operates. A circuit may also be traced from battery on conductor 701, through both windings of relay 7 37 over conductor 738, over the left contact of cam 618, the back contact of the No. 1 counting relay to ground at the lower contact of cam 606. Until the No. 6 counting relay operates a shunt exists around the right winding of relay 737, extending from the jun'ction between the windings th'ereof, over the inner left back contact of relay 737, conductor 739, the upper left contact of cam 619, the lower left contact of cam 609, the back contact of the No. 6 counting relay to ground at the lower contact of cam 606. As soon as the No. 6 counting relay operates this shunt is opened and relay 737 energizes. Still another circuit may be traced rom battery on the conductor 701 conductor 741, the upper contact of cam 620, the back contact of the No. 0 counting relay to ground at the lower contact of cam 606. Until the No. 5 countin relay operates the right winding of relay 40 is shunted in a-' over both windings of relay 7 40,

circuit extending from the junction point between the windin thereof, over the inner left back contact t 'ereof, conductor 742, the

- upper left contact of cam 621, the lower right contact of earn 612, theback contact of the No. 5 countingrelay' to ground at the lower contact of cam 606. As soon as the No.5

counting relay operates this shunt is removed and relay 740 operates.

When the No. 4, No. 3, No. .2 and No. 1 counting relays operate, previously traced operating circuits for relays 7 28, 7 31, 734 and 737 are opened at the back contacts of such counting relays and therefore at the time sequence switch 500 advances out of position 9 into position 10 only one register relay 7 40 of the final tens register remains operated. This relay locks from battery on conductor 7 01, through both of its windings and its in ner right front contact, conductor 743, to ground at the lower left contact of cam 603 as soon as sequence switch 500 reaches position 9%. Upon leaving position 9 the locking circuits for all operated counting relays are opened at the lower contact of cam 606 in readiness for the registration of final units impulses.

With sequence switch 500 in position 10 relay 523 is again 0 erated over the fundamental circuit in serles with relay 112 of the sender 103. In the manner previously described relay 528 operates and locks upon the operation of relay 523, advancing sequence switch 500 into position 11 thereby including relay 529 in the fundamental circuit. Counting relays of the spill sender and of the sender 103 are thereupon operated and locked in the manner previously described until the sender 103 is satisfied as to its final units registration when relay 113 operates opening the fundamental circuit at the sender 103. Thereupon relays 112, 523 and 529 deenergize, relay 523 unlocking relay 528 which in turn deenergizes, advancing sequence switch 500 into position 12. Since it has been assumed that the units digit of the wanted line is three and the line therefore terminates in the fourth set of terminals of the ninth tens group, the No. 9, No. 9, No. 8, No. 8, No. 7, No. 7 No. 6 and No. 6' counting relays will have been operated.

Prior to the advance ofsequence switch 500 out of position 11 a circuit will be effective from battery on conductor 701, through both windings of relay 744, conductor 745, the right contact of cam 611, the back contact of the No. 4 counting relay to ground at the lower contact of cam 606. Until the No. 9 counting relay operates a shunt exists around the right winding of relay 744, extending from the junction between its windings, the left back contact of relay 744, conductor 746, the upper left contact of cam 614, the lower right contact of cam 608, the back contact of the No. 9 counting relay to ground at the lower contact of cam 606. As soon as the No. 9 counting relay operates this shunt is opened and relay 744 energizes. A circuit is also closed from battery on conductor 7 01, through both windings of relay 747, conductor 748, the right contact of cam 613, the back contact of the No. 3 counting relay to ground at the lower contact of cam 606. Until the No. 8 counting relay operates a shunt exists around the right winding of relay 747, extending from the junction between its WlI1dings, over its inner left back contact, 0on ductor 749, the lower right contact of cam 615, the lower left contact of cam 610, the

back contact of the No. 8 counting relay to ground at the lower contact of cam 606. As soon as the No. 8 counting relay operates this shunt is opened thereby and relay 747 operates.

A circuit is also established from battery on conductor 701, through both windings of relay 750, conductor 751, the right contact of cam 616, the back contact of the No. 2 counting relay to ground at the lower contact of cam 606. Until the No.7 counting relay operates a shunt exists around the right winding of relay 750, extending from the junction between the windings thereof, over its inner left back contact, conductor 752, the lower left contact of cam 617, the lower left contact of contact 607, the back contact of the No. 7 counting relay to ground at the lower contact of cam 606. As soon as the No. -7 counting relay operates this shunt is opened and relay 750 operates. A circuit may also be traced from battery on conductor 7 01, through both windings of relay 753, conductor 7 54, the right contact of cam 618, the back contact of the No. 1 counting relay to ground at the lower contacts of cam 606. Until the No. 6 counting relay operates a shunt exists around the right winding of relay 753, extending from the junction of the windings thereof, over its inner left back contact, conductor 755, the lower right contact of cam-619, the lower left contact of earn 609, the back contact of the No. 6 counting relay to ground at the lower contact oficam 606. As soon as the No. 6 counting relay operates this shunt is opened and relay 753 energizes. Still another circuit may be traced from battery on conductor 701, over both windings of relay 756, conductor 757, the lower contact of cam 620, the back contact of the No. 0 counting relay to ground at the lower contact of cam 606. Until the No. 5 counting relay operates the right winding of relay 756 is shunted in a circuit ex tending from the junction between the Windings thereof, over its inner left back contact, conductor 758, the upper right contact of cam 621, the lower right contact of cam 612, the back contact of the No. 5 counting relay to ground at the lower contact of cam 606. Since it has been assumed that the No. '5 counting relay is not energized this shunt is not opened, and relay 756 does not energize. lVhen therefore sequence switch 500 advances out of position 11 into position 12 only register relays 744, 747, 750 and 753 of the final units register remain operated. These. relays then lock as soon as sequence switch 500 reaches position 11 from bat tery on conductor 7 01, over both windings of these relays, the inner right front contact of each, conductor 759 to ground at the upper left contact of cam 603. Upon leaving position 11 the locking circuits of all operated counting relays are opened at the lower contact of cam 606 and these relays deenergize current advances the sender in the well known manner for making talking selection at the district selector whereupon the district selector advances into the talking position and the sender 103 is dismissed. Relay 523 also energizes over the fundamental circuit in turn operating relay 528 which looks and in turn advances sequence switch 500, through position 13 into position 14. As soon as sequence switch 500 leaves position. 13 relays 523 and 528 deenergize.

With sequence switch 500 in position 14 and sequence switch 550 in position 3 as soon as the district selector 102 advances into the talking position a circuit is established from battery through resistance 534, the right 'winding of relay 533, conductor 622, the

- go tor 626 to ground at of cam 115, the upper right windin of repeating coil 117, the winding of re ay 118 the lower right winding of .repeating coil 117, the lower contacts of cam 116, the ring brushes of selectors 102 and 150, trunk conductor 202, conductor 218, brush 524 of trunk finder 520, the left contacts of cam 536, conductor 624, the lower contacts of cam 614, conductor 625 to ground through the left winding of relay 533. Relay .533 energizes in-this circuit but relay 118 eing polarized does not. Relay 533 upon energizing closes a circuit from ground on its front contact over conductor 626, the right contacts of cam 617, conductor 627, to battery through the winding of relay 537 Relay 537 energizes closing at its left front contact a locking circuit for itself extending to ground at the front contact of relay 533 and overconducthe lower contacts of cam 621. At its right front contact relay 537 closes an obviousoperating circuit for relay 538 which upon energizing closes a circuit extending from ground over its outer right front contact, theupper contact of cam 539 to battery through the winding of sequence switch magnet 500 advancing this seuence'switch out of position 14 into posit1on 18.

Incoming brush selection Upon reaching position 15 a circuit is closed from ground at the up of cam 527 over the lower le contact of cam 540 to battery through'the winding of magnet 550 advanclng sequence switch 550 into position 4. With s uence switch 200 in position 2 a fundamenta switch controllin circuit may be traced from the incoming se ector of Fig. 2 to the spill sender, cxtending'from battery through the right winding 0 relay207, the lower contacts of cam 219, conductor 221, brush 541 of-the trunk finder, the left contact of cam 542, the lower contacts-of cam 525, theri ht back contact of relay 526, the winding 0 relay 529, the outer right back contact of relay 543, the contacts of cam 544, conduc tor 628, the baclr contact of the No. 0 counting relay, conductor 629, the contacts of cam 545, theright winding of polarized overflow relay 546, resistance 547, brush 549, conductor 222, to ground at the lower contact of cam 220. Relays 207 and 529 energize 1n this c1r- 'cuit but relay 546 being polarized does not 65 operate. a

Relay 207 upon energizing closes a circu t for advancin sequence switch 200 into POSI- tion 3 exten ing from battery through the magnet winding of sequence switch 200, the upper right contact of cam 216 to ound at the left front contact of relay 207. elay 207 also closes a lockin circuit for itself extending from battery through its right winding, the left contact of cam 223, the rlght front contact of relay 207, the left contacts of cam r right contact 219 to conductor 221 of the fundamental circuit for holding itself energized over the fundamental circuit after sequence switch 200 leaves position 2. With sequence switch 200 in position 3, a circuit is established for the up-drive magnet 224 extending from battery through this magnet, the right contact of cam 225 to ground at the left front contact of rela-y 207 for advancing the switch shaft in its brush selection movement.

shaft approaches the first brush selection position a circuit is closed in shunt of the sender stepping relay 529 which may betracedfrom ground at the left contact of cam 229, commutator brush 226, a conducting segment of commutator strip 227 the lower contacts of cam 223, to battery through the right winding of relay 207 and to conductor 221 of the fundamental circuit over the right front contact of relay 207 and the left contacts of cam 219. Relay 207 is held energized over this circuit but the sender steppin relay deenergizes.

It will be recalled t at relays 700 and 705 of the incoming brush register of the spill sender have been operated and therefore upon the initial energization of, stepping relay 529 over the fundamental circuit just traced a As the switch circuit is established from ground at the left contact'of cam 548, the contact of relay 529, conductor 630, the upper left contact of cam 631, conductor 632, the left back contact of relay 710, the outer right front contact of relay 700 the outer left ront contact of relay 705, conductor 760, the back contact of the No.1 counting relay, the winding of the No.

1 counting relay to battery at the left contact of cam 600. The No. 1 counting relay energizes in this circuit locking through the winding of the No. 1 countin relay through the ri ht front contact of tieNo. 1 counting relay over the lower contacts of'cam 605 to ground at the lower contact of cam 606. The No. 1 counting relay being shunted at this time over the front contact of the stepping relay 529 does not operate. When, however, the stepping relay 529 deenergizes at the time the incoming selector reaches its first brush tripping position, the No; 1' counting relay energizes and extends conductor 760 over its front contact, the contacts of cam 633, the winding of the No. 0 counting relay to battery at the left contact of cam 600."

As the switch shaft of the incoming. selector 250 advances, the brush 226 engages the next insulating segment of commutator strip 227, and the shunt about stepping relay 529 is removed and relay 529 a ain energizes completing the circuit of the%lo. 0 counting relay. .This counting relay now locks through the'winding of the No. 0 countin relay and the winding of relay 634 in paral el over the front contact of the No. 0 counting relay to round at the lower contact of-cam 606. Reay 634 and the No. 0' counting relay do not energize in this circuit until the switch shaft relay 634 energizes a circuit is closed from its front contact over the upper right contact of cam 540through the magnet winding of se quence switch 550 advancing such sequence switch into position 5; In position 5 a circuit is closed through magnet 550, the upper left contact of cam 540, the left back contact. of

relay 526, to ground at the inner right front contact of relay 538, 'for advancing sequence switch550 into position 6. The No. 0 counting relayupon energizing opens thefundamental circuit at its back contact thereby releasing stepping relay 529 and relay 207. As

. the sequence switch 550 advances out of position 4 the locking circuits of the operated counting relays are opened'at the lower con 'tacts of cam 605.

Incoming group selection At the incomingselector relay 207 is held energized over the circuit previously traced to ground over the brush 226 until the switch shaft has been positionedto enable the second set of brushes to be tripped, when the brush 226 will engage an insulating segment of commutator strip 227; Relay 207 upon.

deenergizing'opens the circuit ofthe up-drive magnet 224- and closes a circuit extending from battery through the winding of sequence switch magnet 200, the upper left contact of cam 216, to ground at the left back contact of relay 207 for advancing sequence switch 200 out of position 3 into position 3. 'In position 4 a circuit is closed for the trip'magnet 228 extending from battery through magnet 228 to ground at the right contact ofcam 229. Also. in position v4 the fundamental circuit previously traced is again closed and relays 207 and 529 energize thereover. Relay 207 upon energizing again closes the -previously traced circuit for advancing sequence switch 200 out of position 4 into position 5, locking itself to the fundamental circuit in" the manner previously described.

With se uence switch 200 in position'5 the,

circuito the up-drive magnet 224'is again closed over the front contact of relay 207 for advancing. the switch shaft in its group selection movement.

- During the initial portion of the group selection movement of the switch shaft the second set of brushes is tripped in the wellknown manner. I As the switch shaft approaches its first group selection position the rush 230 engages the first conducting segment of commutator strip 231 closinga cir-' cuit for relay 207 extending from ground at the left contact of cam 229, brush 230, commutator strip 231, the upper contact of cam- 223 to battery through t e right winding of relay 207, This circuit being in shunt of the At the sender upon the reestablishment of the fundamental circuit for controlling incoming group selection relay 529 energizes and since it has been assumed that no incoming group register relays are at the time energized a circuit is established from ground at the front contact of relay 529 over conductor 630, the upper rightcont-act of cam 631, now in position 6, conductor 635, the right back contact of relay H711, the right back contact of relay 715, conductor 761, the back contact of the No. 3- counting relay to battery through the Winding of the N o. 3 counting relay and the left contact of cam 600. The No. 3 counting relay energizes and locks through the winding of the No. 3 counting relay and its own front contact to. ground at the lower contact of cam 606, but the No.

3 counting relay being shunted does not enof the incoming selector advances the shunt about relay 529 is intermittently established and broken until the counting relays including No. 0 and No. 0 relays and relay 634 become energized in the manner previously described. At that time the brush shaft of the incoming selector will have been positioned at the bottom of the fourth or upper brush group accessible to the tripped set of brushes Upon the energization o relay 634 the sequence switch 550 is again advanced out of position 6 into position 8 over the circuits previously traced, unlocking the operated I counting relays, and the fundamental circuit is opened at the back contact of the No. 0 counting relay. As soon after the opening of the fundamental circuit as the commutator brush 230 engages an insulating portion of strip 231 relay 207 releases opening the circuit of the up-drive magnet 224 and advanc- I ing'sequence switch 200 into position 6. In position 6 a circuit is established from ground at the upper contact .of cam 214 to battery through the left winding of relay 207, where upon relay 207 energizes. At its left front contact relay 207 closes the previously traced circuit for advancing sequence switch 200 into position 7. As the sequence switch leaves position 6 4 the energizing circuit of relay 207 is opened at cam 214, but relay 207 re mainslocked upover its right winding, the left contact of cam 223, the right front contact of relay 207, the upperjcontacts of cam 232, sleeve brush 233 to ground on the sleeve terminal of the first trunk of the selected group, if the trunk upon which the brushes 233,235, and 236' are standing is busy, In

that event, relay 207 establishes a circuit over over the lower left contact of cam 225 and the left front contact of relay 207. When the brushes are properly centered relay 207 deenergizes opening the circuit of the up-drive magnet 224 and advancing sequence switch i 200 into position 8 7 lower left contacts of cam 240 to ground. As

Until the se uence switch 200 reaches position 8 groun is placed on the sleeve terminal of the selected trunk over brush 233, the upper contacts of cam 232. the right back contact of relay 207, the upper right and soon as sequence switch 200 reaches position 7 direct ground isconnected to brush 233 over the right contacts of cam 232. In position 8 a circuit is established from battery,

' front contact of relay 207,

through the right winding of relay 207, the lower right and upper left contacts of cam 219 to ground over the upper left and lower right contacts of cam 232. Relay 207 energizes and closes the previously traced circuit for advancingsequence switch 200 into the selection beyond position 9. After the sequence switch 200 leaves position 8, relay 207 remains energized over a'holding circuit extending from battery throughits right winding, he left contact of cam 223, right the upper contact of cam 242, brush 236, conductor 306, the upper left and lower right contacts of cam 307 to ground at the lower left contact of cam 338.

F inal brush. selection A fundamental switch controlling circuit is now established from the final selector 350 to the sender which may be traced from bat-- tery, upper contact of cam 301, right winding of relay 302, lower left contact of cam 303, lower left contact of cam 304, conductor. 305, brush 235, lower left contact of cam 241, thence as previously traced over conductor 221, through the winding of sender stepping ground at the lays Relay 302 upon energizing locks in a circuit from battery over the upper contact of cam 301, its right winding, the upper contact of cam 308, the inner left front contact of relay 302, the upper left contact of cam 303, thence over the fundamental circuit, and closes a circuit extending from battery through'the left winding of relay 310, the left contact of cam 311, the outer left front contact of relay 302 to ground at the lower' left contact of cam 312. Relay 310 energizes and locks through its left winding, the back contact of relay 313, the left front contact of relay 310, to ground on sleeve conductor 234 and at its right front contact establishes a circuit from ground over thelower contacts of cam 309 to battery through the magnet winding of sequence switch ing the sequence switch into position 2. With 300 for advanc sequence switch 300 in position 2-and relay 302 energized a circuit is closed for the big speed up-drive magnet 314 which may be traced from battery through the magnet 314, the upper contact of cam 315, the outer left 'front contact of relay 302 to ground at the lower left contact of cam 312. Magnet 314 upon energizing causes the switch shaft to be moved upwardly in its brush selection movement. 0

During the upward movement of the switch shaft an intermittent ground is connected to.

the fundamental circuit for intermittently shunting the stepping erlay 529 of the sender over a circuit which may be traced from trunk conductor 305, thelower left and upper right contacts of cam 304, commutator strip 316, brush 317 to ground at the lowenright contact of cam 338. On the initial closure of the ndamental circuit relay 529 energizes and since it has been assumed that rela 724 of the final brush re 'ster of the sen er is at the time energize a circuit is established from ground at the left contact of cam 548,

contact of relay 529, conductor 630, the lower left contact of cam631, conductor 636,.the left front contact of rela 724, conductor 762, the a back contact of the o. '4' countin relay to battery through the winding of t e No. 4 ,countin relay and theleft contact of cam 600. T e No. 4 counting relay looks over a circuit through the windin counting relay and its own ront contact in the manner previously described, the No. 4' counting relay operating in this locking circuit upon the first deenergization of relay 529. Inresponse to the intermittent shuntin ofrelay 529 as the final selector brush sha advances, successive counting relays are ope'rated until the No. 0' relay and relay 634 operate at which time the brush shaft of the final selector will have advanced to position Relay 634 upon ener 'zin closes the previously tracedcircuits or advancing the seuence-switch 550 out of posit-ion 8 intoposi tion 10, the operated count-ing rela being released when such, sequence switchleaves position 8. The No. 0' counting relay upon 0 erating opensthe fundamentalcircuit prevlously traced throu h the windings of relays 302 and 529. ntil the selector switch shaft reaches a position in which the fourth brush set may be tripped, relay 302 is held energized over the previously traced shunt path extendin to ground over the commutater brush -31 Belay 302 thereupon deenof the No. 4'

its fourth set of brushes for subsequent triprelay 529, returning over conductor 222 to p 1 lower contact of cam 220. Re- 302 and 529 energize in this circuit- 

